Police have charged a Dover Air Force Base, Del., staff sergeant with murder by abuse or neglect in connection with the death of fellow airman’s 21-month-old toddler.

Staff Sgt. Justin Corbett, 25, was arrested Tuesday and is being held at the James T. Vaughn Correctional Center in Smyrna, Del., on a $100,000 cash bond, according to online jail records.

Corbett and his wife, Aubrey, were helping to care for Evan Dudley while his mother was deployed to southwest Asia from May to November 2012. The child care plan was approved by the Air Force.

Corbett and Evan’s mother, Staff Sgt. Nikki Dudley, belonged to the same squadron at Dover, Dudley said in an interview with Air Force Times in September.

Dudley was weeks away from returning home from her deployment with the 436th Logistics Readiness Squadron when she learned Evan had been injured, she said. While she made her way back to the United States, Delaware state police began investigating Corbett, who placed a 911 call Nov. 3, 2012, according to a search warrant.

Corbett told police Evan “fell down eight carpeted stairs.”

Evan, whose injuries included head trauma and multiple contusions on his body, died at a hospital four days later.

After months passed with no arrest last year, Dudley took her story to Facebook and to the online petition platform Change.org, where she called on Delaware Attorney General Beau Biden to bring her son’s case to resolution.

An autopsy revealed Evan died from blunt force trauma, Delaware State Police said in a news release Wednesday.

“After a thorough and comprehensive investigation by the Delaware State Police and review by the Delaware Attorney General’s Office, the case was submitted for review to a child abuse expert and pediatric pathologist due to the discovery of undisclosed unique injuries noted during the autopsy. After their lengthy review and evaluation of the complex case, both experts agreed that the child was the victim of a homicide,” the news release said.